The present invention relates to a cleaning device for removing extraneous substances, such as toner, particles of paper and the like, which have become attached onto or remain on a surface of a member to be cleaned, and to an electrophotographic apparatus having the cleaning device.
The known construction of a cleaning device for an electrophotographic apparatus, such as a typical laser printer or a copying machine, is that a cleaning brush is supported rotatably around a shaft inside a housing, a part of the cleaning brush is exposed through an opening provided in the housing, the cleaning brush exposed through the opening in the housing is caused to rub against a surface of a member to be cleaned, such as a photosensitive drum, to remove extraneous substances, such as toner and particles of paper, from the surface of the member to be cleaned.
In a cleaning device of this kind, even though the extraneous substances are at first collected into the housing of the cleaning device by the cleaning brush, part of the extraneous substances are sometimes carried by rotation of the cleaning brush and again discharged onto the photosensitive drum surface through the opening in the housing, resulting in the contamination of the inside of the machine. Therefore, it has been considered effective in preventing extraneous substances collected inside the housing from leaking into the area of the photosensitive drum by arranging an electrode at an inner surface of the housing so as to form an electric field curtain by applying a voltage to the electrode, as disclosed, for example, in Japanese Patent Application Laid-Open No. 63-3157.
If the cleaning brush could certainly scrape and collect extraneous substances, such as toner and so on, from the surface of the photosensitive drum into the inside of the housing from an extraneous substance removing region where the cleaning brush acts on the photosensitive drum, the construction disclosed in Japanese Patent Application Laid-Open No. 63-3157 would be satisfactory. However, in actual practice, it is impossible to collect all the extraneous substances into the inside of the housing in the extraneous substance removing region, and so there exist floating extraneous substances in a scraping portion between the cleaning brush and the photosensitive drum.
The floating extraneous substances flow out along the rotating photosensitive drum to attach onto a charger arranged in a downstream portion in the rotating direction of the photosensitive drum with respect to the cleaning device, or part of the floating extraneous substances again attach onto the surface of the photosensitive body. This causes contamination of the inside of the electrophotographic apparatus. Further, the toner attached onto the charger and the toner attached onto the surface of the photosensitive drum not only contaminate the inside of the electrophotographic apparatus, but cause a degradation of printing quality.